This invention is related to a process for manufacturing microcapsules, which are particularly useful for thermo-changeable color ink changing color when raising or lowering temperatures from room to specified temperature or for color ink for carbonless paper.
Further, this invention can be applied to a process for manufacturing capsules of perfumes, agricultural chemicals, and curing agents for adhesives.
Up to now, there has been many processes for manufacturing capsules for thermo-changeable color ink or carbonless paper ink. Particularly, a process for forming film from urea- or melamine-formaldehyde copolymer using ethylenemaleic anhydride copolymer as a system modifier (patent announcement No. Showa 54-16949) has been widely used.
However, when applying the microcapsules manufactured by the above-mentioned process to thermo-changeable color ink, the marked differences in temperature were observed between the brightness of changed color, the color change in raising temperature, and the color return in lowering temperature.
The present invention provides a process for manufacturing capsules wherein the above-mentioned defects are improved, the manufacturing process is shortened, the capsules of uniform particle size are gained, and no deterioration of dyestuff occurs.